roof tile, tiled roof
甍 centers on the ridge of a tiled roof, specifically the decorative ridge tiles that cap the roof. The meanings 'roof tile' and 'tiled roof' both point to this architectural feature.
甍 combines 瓦 (tile) with a phonetic component that originally represented a roof ridge. The character specifically refers to the ridge tiles of a roof.
The bottom 瓦 is a tile, and the top part looks like a roof with a ridge (⺾ as grass/thatch, 冖 as cover, 罒 as a net or framework). Picture a tiled roof with a prominent ridge line.
For ボウ, imagine a bow-shaped roof ridge: the curved ridge tiles form a bow (ボウ) along the top of the tiled roof.